Cross-bar switch for use in automatic telephone systems



Oct. 30, 1951 G- B. KNOS 2,573,453

CROSSBAR SWITCH FOR USE IN AUTOMATIC TELEPHONE SYSTEMS Filed Feb. 12, 1949 INVENTOR. GUNNAR 1301261310105.

AGENT.

Patented Oct. 30, 1951 CROSS-BAR SWITCH FOR USE IN AUTO- MATIC TELEPHONE SYSTEMS Gunnar Biirge Kniis, Eindhoven, Netherlands, as-

signor *to Hartford National Bank and Trust Company, Hartford, Oonn., as trustee Application February 12, 1949, Serial No. 76,158 IntheNetherlands March 15, 1948 4 Claims.

.The instant application is .a continuation-inpart of the copending application by the same inventor filed onDecember '6, 19.47, and given Serial Number 790,085.

The invention relates to improvements in or modifications of .the invention described and claimedin said copending application. In this copending application is described a cross-bar switch of thekind comprising contact wires for automatic telephone systems and the movable contact bodies of which are constituted by metal wires bent in a labyrinthine manner "(movable contact wires) and crossing all the stationary contact wires of a grid opposite the contact areas. These movable contact wires exhibit a number of bows (contact bows) located in the same plane and engaging linking members and .are supported between them by stationary supports. On a linking member being moved across the planeof the contact bows, the tips of the contact bows bearing on these linking members are moved and engage the stationary contact wires withwhich they co-operate.

The cross-bar-switch according to theaboveidentified copending application may be .constructed so that the linking members must exercise .a force on the contact bows to bring them into engagement with the stationary contact wires. As an alternative, the movable :contact Wires may be given already in their position of rest a mechanical stress which tends to move the contact bows towards the stationary contact wires. In this case the linking members must exercise a force on the contactibows to keep them clear of thestationary contact wires. In order that this stress may be obtained the pieces of the-wirewhich link the contact 'bowsito one another must be fixed on the stationary supports.

This is required even in'the first case in'order -to-prevent the force exercised by a linking mem- -ber-ona contact bow from being transferred by way of the adjacent contact bows to the linking members (so-operatingtherewith and from shift- "ing said-linking members or warping the contact bows.

It has been suggested in the above-identified :copending:applicationto provide-the movable contact wires not only with contact bows but also with secondary bows by means of which they are secured to the stationary supports. Since they serve to stress the movable contact wires they are referred to as stressing bows. But for these stressing bows, to secure the movable contact wires would require a great clamping force. The stressing bows furnish a lever arm for the re" active force, which is thus enabled to be mate- .rially reduced.

In the embodiments shown in'the drawing accompanying the above-identified copending ap plication the contact bows exhibit a shape bent outwardly over the stressing'bow. This-permits of the stationary contactwires *of two adjacent channels being brought into closer proximity and of the dimensions of the assembly being thus reduced.

It has furthermore been pointed out already in the above-identified copending application that it is possible .for the stressing bows tightly to embrace the supports. Although not being indispensable, it has the advantage that the linking members are subject to forces in their own direction only and need not also act to prevent the stressing bows from slipping out of the notches in the supports. Upon a contact wire constructed in this manner being positioned, the insertion of a support in a stressing bow has theefiect of spacing the arms of this bow 'further apart and then causing them to slide .pinchingly on either side along the support till the inwardly bent feet of the stressing bow have reached the end of the support and snap around it resiliently. In this case more or less rough handling may damage the wires of thesupports and this'is avoided by the use of the invention.

It relates to an improvement in a cross-bar witch according to the above-identified copending application in which the "movable contact wires are provided with stressing hours. In the cross-bar switch according to the invention "the contact bows supply a force which holds the stressing bows in place on the supports. This force is produced in that in the'contact bows is available a bending stress which tends to force apart the feet of these bows. When providing a movable contact wire on a support, the arms-of the contact bow require to be clamped but there is-no need for th'estressing bow to bebent open to any appreciable extent. This permits of the stressing bows being put on the supports without any appreciable friction. Not until it has been positioned, is a stressing bow fixed in position'by causing the next "following to surround support.

The arms of the contact bows shown in the drawing accompanying the above-identified copending application are parallel and they are interconnected at the end by an eyelet. For clamped contact bows this form is less suitable, *since it requires that prior to the stressing operation the tips of the contact bows should not be located on a straight line but instead on a circle 01' helix, which renders manufacture more dinicult. With a cross-bar switch according to the invention, it is of advantage to shape the stressed contact bows into the form of anisosceles triangle the apex of which lies at the feet of the bow, or into the form of a spatula. If the 'bow height is the same, the required deformation-is smaller and the bow is-less rigid. In addition, the'wires-are stressed more readily.

In order that the-invention may be more clearly understood and readily carried into effect, it will now be described with reference to the accompanying drawing, in which Fig. 1 shows, on 'an'enlarged scale, *by 'way "of example, partof a movable contact wire of a cross-bar switch according to the invention, viewed in the direction of movement of the linking member.

Fig. 2 is a sectional view taken on the line II--II.

Fig. 3 is a sectional View taken on the line IIIIII.

Fig. 4 shows the shape of the same wire before being stressed.

Fig. 5 shows an alternative form of the contact bows.

As may be seen from Fig. 1, the contact bows, apart from small curvatures due to the stressing operation, are shaped into the form of an isosceles triangle, the apex of which lies at the feet of the bows. The contact piece I which extends along the base of this triangle bears on the wall 2 of a notch in the linking member 3. The contact bows are separated by stressing bows 4, which bear on the wall 5 of a notch in combs 6. These combs 6 connect strips 1 which leave gaps 8 in which are located pieces 9 of the wire which connect the stressing bows to the contact bows. made of insulating material.

Assuming the projection plane of Fig. 1 to be Linkin members, combs and strips are horizontal and that of Fig. 2 to be vertical, the

to bear on the wires l0 with a contact pressure which is supplied by the resilient force of the movable contact wires.

According to the invention, the movable contact wires have a tension also in a horizontal direction, this tension being directed so as to tend to separate the arms I l of the contact bows. Prior to the stressing operation, the wires are in appearance as shown in Fig. 4, the contact tools than into a form in which the contact pieces extend beyond the feet of the bows. By putting the wire on the combs 6, the arms II are urged towards one another and the triangular shap bows having a rectangular form into which they are more readily shaped with the use of simple into which the contact bows of Fig. 1 are formed is produced. The pieces 9 are urged against the combs 6 by the resilient force of the contact bows with the result that the feet 12 of the stressing bows clasp the combs. The wire is thus pre vented snapping from the combs and need not be held by the linking member.

Prior to the stressing operation the feet [2 of the stressing bows are spaced apart to such an extent that the combs fit between them. In Fig. 4 one of the combs 6 is shown in broken lines to illustrate this. Consequently there is no need for the wire to be slipped forcibly over the combs but may be put on it without any appreciable friction.

The stationary contact wires [0 are arranged in pairs. Each contact bow co-operates with two stationary contact wires of the same pair. The linking members are invariably arranged between the wires of each pair. vided with key-shaped extensions 13 which serve ;to urge the stationary contact wires, after the They are pro- 7 4 contact bows have been brought into engagement therewith, slightly apart during the further movement of the linking member. The wires are thus caused to slide over the contact pieces I and the points of contact are cleaned by friction.

What I claim is:

1. In a cross-bar switch for automatic telephony provided with a planar grid constituted by a group of paired linear conductors disposed in spaced relation and serving as the passive contacts of said switch, an active contact structure comprising a plurality of resilient wires disposed in spaced positions transversely with respect to said conductors, each wire being fiexiously shaped to form alternate active contact bows and stressing bows, each of said active bows intersecting a respective pair of conductors, and a supporting comb for each of said stressing bows, successive combs for the stressing bows having a spacing therebetween which is smaller than the spacing between the corresponding stressing bows of the wire before they are attached to the combs, each of said contact bows having a pair of side arms which when urged together and then released when said stressing bows are received by said combs impart a resilient force against the adjacent stressing bows to cause said stressing bows securely to clasp their associated comb.

2. An arrangement, as set forth in claim 1, wherein the shape of each contact bow is such that when the arms are urged together the contact bow assumes substantially the shape of an isosceles triangle.

3. An arrangement, as set forth in claim 1, wherein the shape of each contact bow is such that when the arms are urged together the contact bow assumes substantially a spatulate contour.

4. In a cross-bar switch for automatic telephony provided with a planar grid constituted by a group of paired linear conductors disposed in spaced relation and serving as the passive contacts of said switch, an active contact structure comprising a plurality of resilient wires disposed in spaced positions transversely with respect to said conductors, each wire being flexiously shaped to form alternate active contact bows and stressing bows, each of said active bows intersecting a respective pair of conductors, and a supporting comb for each of said stressing bows successive combs for the stressing bows having a spacing therebetween which is smaller than the spacing between the corresponding stressing bows of the wire before they are attached to the combs, each of said contact bows having a generally rectangular configuration defined by a pair of parallel side arms interconnected at the ends by a cross arm, whereby when said side arms are urged together and then released when said stressing bows are received by said combs, they impart a resilient force against the adjacent stressing bows to cause said stressing bows securely to clasp their associated combs.

GUNNAR BC'JRGE KNos REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

